US 6851100 B1
An integrated management system is provided for automatically executing a procedure of reviewing and editing an assembly reference and a bonding specification used for manufacturing IC packages. The system includes a drawing management system (DMS) that creates the assembly reference, and a bonding specification drawing system that creates, based on the assembly reference, the bonding specification. The integrated management system further includes a DMS database server that stores and manages the assembly reference and the bonding specification, a DMS file server that manages a blank diagram, a package outline, a bonding diagram, and a standard file, and a DMS web server that provides a web interface to a user for permitting a remote access. In particular, the drawing management system has a bonding rule check module that verifies whether the bonding specification meets a bonding rule suitable for an automated wire bonding process. The drawing management system produces the standard file to be transmitted to bonding equipments.
1. An integrated management system structured to automatically execute a procedure of reviewing and editing an assembly reference and a bonding specification used for manufacturing IC packages, said system comprising:
a drawing management system structured to output the assembly reference including a bonding diagram, a package outline, a package pin configuration, and package pin coordinates;
a bonding specification drawing system structured to output, based on the assembly reference, the bonding specification including a chip size of a chip, an electrode pad size for each electrode pad on the chip, an electrode pad position of the each electrode pad, a die pad size of each die pad, a die pad position of the each die pad, a length of each bonding wire, a position and an angle of the each bonding wire, a bonding sequence, a datum point for the each electrode pad, a datum point of each lead, a central point for the electrode pad, and a bonding attach point of the lead;
a database server structured to store and manage the assembly reference and the bonding specification;
a file server structured to manage an information diagram for a standard component, the package outline, the bonding diagram, and a formatted output file; and
a web server structured to provide a web interface to a user seeking to establish a remote access with the drawing management system,
wherein the drawing management system comprises a bonding rule check module structured to verify whether the bonding specification meets a bonding rule suitable for an automated wire bonding process, and wherein the drawing management system is structured to transmit the formatted output file to a bonding apparatus.
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31. A method of automatically executing a procedure of reviewing and editing an assembly reference and a bonding specification based on the assembly reference, wherein the assembly reference and the bonding specification are used for manufacturing IC packages, said method comprising:
producing the assembly reference with a drawing management system, the assembly reference comprising a bonding diagram, a package outline, a package pin configuration, and package pin coordinates, wherein producing the assembly reference further comprises verifying whether the bonding specification meets a bonding rule suitable for an automated wire bonding process using a bonding rule check module;
producing the bonding specification with a bonding specification drawing system, the bonding specification comprising a chip size of a chip, an electrode pad size for at least two electrode pads on the chip, an electrode pad position of the at least two electrode pads, a die pad size of a die pad of the chip, a die pad position of each die pad, a length of each bonding wire, a position and an angle of each bonding wire, a bonding sequence, a datum point for each of the at least two electrode pads, a datum point of a lead, a central point for each of the at least two electrode pads, and a bonding attach point of the lead;
storing and managing the assembly reference and the bonding specification with a database server;
managing an information diagram for a standard component, the package outline, the bonding diagram, and a formatted output file with a file server;
establishing a connection between the drawing management system and a remote user with a web browser interface; and
transmitting the formatted output file to a bonding apparatus.
This application claims priority to Korean Patent Application No. 2002-12895, filed on Mar. 11, 2002, the contents of which are hereby incorporated by reference in their entirety.
1. Field of the Invention
The present invention relates to semiconductor integrated circuit (IC) assembly technology, and more particularly, to a system for integrally managing data required for an automated wire bonding process.
2. Description of the Related Art
The assembly technology used for packaging and interconnecting electronic components is becoming a highly important field that affects the efficiency of computers or other kinds of electronic systems. A semiconductor chip package assists a semiconductor IC chip to be settled in the electronic system, and provides proper surroundings to guarantee good reliability and suitable operation of the IC chip. The package also electrically connects the IC chip with the electronic system.
With conventional plastic packages, a detailed description of the package assembly process is given below. The package assembly process begins with a wafer in which a great number of circuitries are already formed through the wafer fabrication process. The wafer is subjected to an electric die sorting (EDS) test. Depending on the result of the EDS test, failed dies (i.e., poor IC chips) in the wafer are marked with ink. The wafer is then sawed and divided into individual IC chips. A passed die (i.e., good IC chip) is bonded to one portion of a package base, for example, a die pad of a lead frame. This die bonding process typically; includes a step of coating adhesive material such as silver-poxy onto the package base, a step of placing the IC chip on the package base and a step of curing adhesive material. Thereafter, wires electrically connect the IC chip with another portion of the package base, for example, leads of the lead frame. Tape automated bonding or flip chip bonding can be alternatively used for such electrical connection. The IC chip and the package base are encapsulated in a plastic body by molding. Outer ends of the leads are bent into a suitable form, and a product number, etc. is marked on the plastic body. The finished package is then subjected to tests in reliability and electrical properties.
In the package assembly process, the wire bonding technology is most widely used for electrical interconnection between the IC chip and the lead frame. The wire bonding process should attain high throughput and economical production yield. For this reason, a high-speed wire bonder having a handling system and an image sensing system is generally employed. The handling system supplies the lead frame to a worktable, and the image sensing system permits the IC chip to coincide with a bonding diagram. An automatic thermosonic bonding is a high yield interconnection process that uses heat and ultrasonic energy to form a metallurgical bond. Typically, a gold wire is used and a ball bond is formed at one end and a stitch bond at the other. A ball is formed on the tail of the wire which extends from the end of a capillary. A hydrogen flame or an electronic spark may be used to form the ball. The capillary descends and presses down the ball onto an electrode pad of the IC chip while ultrasonic vibration is applied. After the ball is bonded to the IC chip, the wire forms a loop by sequential actions of the capillary. Then, the capillary deforms the wire against the lead of the lead frame, producing a wedge-shaped bond. The cycle is completed and ready for the next ball bond.
As described above, the wire connects the electrode pads and the leads one by one. Therefore, the high-speed wire bonding process requires information on both a chip layout and a lead frame structure. Further, there is a need for integrated management of both chip layout data and lead frame design data.
In order to enhance the production yield of the package assembly process, especially the wire bonding process, a good design rule of the IC chip should be primarily established and observed. The design rule has to accord with a specific type of the package to be manufactured and should be fitted to current assembly equipments. Further, it is desirable that the determination of the design rule is made before chip laying-out. As the size of the IC chip is reduced and the number of input/output pins is increased, an area necessary for electrical connection influences a chip size. In other words, reductions are required in electrode pad size, pad pitch, process tolerance, etc. Moreover, the chip layout directly influences automation and reliability of the assembly process. It is therefore preferable to incorporate the design rule into a chip layout CAD (computer aided design) system. For example, a wire bonding template that indicates ball bond and stitch bond positions based on the design rule is preferably used for the plastic package assembly process. By overlapping the template and the chip layout, a design engineer can determine desirable positions of the electrode pads.
For automation of the assembly process, it is also essential to apply data in each assembly step to subsequent assembly steps without additional modification or processing. A related technique is disclosed in U.S. Pat. No. 6,256,549 issued to Cirrus Logic, Inc. Herein, a computerized database includes a table representing a list of part numbers. The database provides computerized links between individual part numbers and associated manufacturing process data for different process steps or that part number. Rather than correlate data by hand, a user may click on a process step for a particular part number to instantly and accurately retrieve that data. Manufacturing process data may include wafer back-lapping process data, wire bonding data, testing parameters, packaging data, and marking data.
Another technique related to assembly automation is disclosed in U.S. Pat. No. 5,608,638 issued to Advanced Micro Devices. Herein, a system and method including a user interface for automation of a build sheet is provided. The database icon or command of the user interface is executed to select an appropriate package for an IC chip, and a blank bond master is downloaded to the hard disk of the workstation. The engineer can choose either the suggest die icon/command or the die cleaner icon/command to create an image file of the die pad ring based on a mask layer best representative of the die pad ring. Thereafter, the die pads and bond fingers are, identified and a net list is complied when the wire bonding icon or command is executed to create a bonding device diagram without the die image. A die image is created based on a mask layer best representative of the die using either the TIF to AutoCAD icon/command or the GDS to AutoCAD icon/command. The Die Image Merge icon/command merges the die image with the bonding device diagram to complete the build sheet. Thereafter, an IC package may be fabricated based on the bonding device diagram.
Though such conventional automation techniques may be helpful to an engineer who makes a bonding diagram for the automated wire bonding process, a design or product engineer engaged in mass production line for packaging numerous kinds of IC chips still needs much more improved automation technique. Additionally, a chip layout designer and a lead frame designer seldom benefit by conventional automation techniques. Further, if there is no particular platform, e.g., UNIX workstations, adapted for conventional techniques, an engineer or a designer has difficulty in using the automation techniques. Further, additional manual work is needed to utilize design data or assembly data, created by a CAD drawing tool operating at existing workstation platforms, as Assembly Reference or Bonding Specification at actual mass-production lines. Unfortunately, this requires excessive manual labor and time consumption, and may cause unexpected human error.
In a preferred embodiment, an integrated management system is provided for automatically executing a procedure of reviewing and editing an assembly reference and a bonding specification used for manufacturing IC packages. The system comprises a drawing management system (DMS) that creates the assembly reference, and a bonding specification drawing system (eSPEC) that creates, based on the assembly reference, the bonding specification. The assembly reference has a bonding diagram, a package outline, a package pin configuration and package pin coordinates. The bonding specification has a size of a chip, a size and a position of an electrode pad of the chip, a size and a position of a die pad, a length of a wire, a position and an angle of the wire, a bonding sequence, a datum point of the electrode pad, a datum point of a lead, a central point of the electrode pad, and bonding teach point of the lead.
The integrated management system further comprises a DMS database server that stores and manages the assembly reference and the bonding specification, a DMS file server that manages a blank diagram, the package outline, the bonding diagram, and a standard file, and a DMS web server that provides a web interface to a user for permitting a remote access. In particular, the drawing management system comprises a bonding rule check module that verifies whether the bonding specification meets a bonding rule suitable for an automated wire bonding process. The drawing management system produces the standard file to be transmitted to bonding equipments.
Preferably, the drawing management system may provide an assembly reference review and an assembly reference edit. The drawing management system may also provide a pre-bonding, a batch modification, an administrator menu, an information menu, etc. Additionally, the DMS database server can store bonding rule data. The DMS file server can produce a chip pad file from chip layout data and sends the chip pad file. The chip pad file may include dimensions of the chip, a size of an opening on the electrode pad, arrangement and number of the electrode pads, a pitch between the electrode pads, and a width and a length of a scribe line. The DMS web server can provide a blank diagram database, a package outline database, and a bonder viewer. The bonder viewer may display the bonding diagram retrieved through the DMS filer server according to bonding procedure.
The system of the present invention may further comprise a CAD data processing module, which performs a centering operation. The bonding rule check module has bonding rules based on a pitch between the electrode pads. Preferably, the bonding rules includes rules related to a bonding pad opening (BPO), an electrode pad layout for fine pad pitch, a chip pad design by pad pitch, a bonding wire, and a chip dimension.
The system of the present invention may further comprise a blank diagram building module, which includes a reader, a creating module, and a writer. The system may also comprise a package outline building module, which includes a reader, a creating module, and a writer. Similarly, the CAD data processing module may include a reader, a data processing unit, and a writer. The CAD data processing module can create a standard bonding diagram and send the standard bonding diagram to a bonder viewer module. In addition, the BRC module may include a reader, a BRC unit and a writer. The BRC module can provide automatic wiring operation based on a chip pad file, or gate array processing operation which builds verified chip layout data into a chip pad file to meet a user's request.
The present invention will be now described more fully hereinafter with reference to accompanying drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiment set forth herein; rather, this embodiment is provided so that this disclosure will be thorough and complete, and will filly convey the scope of the invention to those skilled in the art.
Among terms used in this specification, a ‘Specification’ means a standard, which should be observed for making and using semiconductor IC products. A ‘Reference’ designates documents including basic information required for making the semiconductor IC products. For example, a ‘Design Specification’ (hereinafter, referred to as ‘Design Spec’) defines operational voltage, current, speed, and timing relations between internal signals or internal and external signals, etc. Further, a ‘Bonding Specification’ (hereinafter, referred to as ‘Bond Spec’) includes chip size, electrode pad size and position, die pad size and position, wire length, position and angle, bonding sequence, electrode pad datum point, lead datum point, electrode pad central point, lead bonding teach point, etc. An ‘Assembly Reference’ (hereinafter, referred to as ‘Assy Ref’) indicates basic information necessary for assembly of IC products, especially, the automated wire bonding process, and includes bonding diagram, pin configuration, package outline, package pin coordinates, bonding rule check result, etc.
The Assy Ref is based on a Design Spec, which is based on a development standard. The Assy Pef is used for documentation process in DMS 200 and provides basic information for packaging IC products, especially, the wire bonding process.
The DMS 200 includes an administrator menu 220, a user menu 240 and an information menu 260. The administrator menu 220 is for database construction and management. Through this menu 220, a user having authority of administrator creates and manages a package outline DB 221, a blank diagram DB 222, a gate array DB 223, a classification index 224, a bonding rule management 225, and a general information 226. Herein, data stored in the blank diagram DB 222 are not limited to lead frames used for typical plastic packages, rather, include other kinds of package bases such as a printed circuit board (PCB). The package outline DB 221 includes the definition of package pins, a position of the first pin, pin numbering, etc. The blank diagram DB 222 includes a position of a die pad, information on leads, a datum-point of the lead for a wire bonder, and bonding teach points on the leads. The blank diagram DB 222 may be divided into separate databases according to package types. The gate array DB 223 includes design data on the position of the finished die pad. The classification index 224 indicates how to sort various kinds of data stored in the databases.
The user menu 240 includes a pre-bonding 241, a batch modification 242, an Assy; Ref review 243, and an Assy Ref edit 244. The pre-bonding 241 provides a function of simulation for the wire bonding in order to check and correct errors of the bonding diagram designed prior to the completion of the Assy Ref. The pre-bonding 241 may also have an additional function that displays a list according to electrode pad size when a user enters specific chip size and/or package type, and that permits a user to easily select desired pad size. The batch modification 242 provides a function that, when parts of bonding positions are changed in a certain group of products, can modify a set of data equivalent for the change in a single program run. The Assy Ref review 243 provides a function that a user can review or search the Assy Ref already made. And the Assy Ref edit 244 includes functions of drawing and registering new Assy Ref and modifying or deleting the Assy Ref stored in the database. All data corresponding to new, modified or deleted Assy Ref are automatically uploaded to servers of the system.
The function of the administrator menu 220 and the user menu 240 is not limited to the above-described functions. A person skilled in the art will appreciate that other types of functions can be used for implementing the present invention as long as it is within the spirit and scope of the present invention.
The information menu 260 of the system 100 is optional and may include a bonding rule help 261 and a CAE (computer aided engineering) file management 262. The bonding rule help 261 provides an explanation for the bonding rule, so that a designer entering the DMS 200 can refer to detailed bonding rules, such as electrode pad size, corner pad pitch, distance between adjacent wires, and wire length and angle, during the design or the Assy Ref review or edit. The CAE file management 262 has a function of managing plenty of data files produced for the assembly process. For example, a chip layout in
The eSPEC 300 of the system 100 includes a user interface such as a Bond Spec review 320 and a Bond Spec edit 340. Like the Assy Ref edit 244, the Bond Spec edit has functions of drawing and registering new Bond Spec and modifying or deleting the Bond Spec being registered in the database. As described above, the Bond Spec includes chip size, electrode pad size and position, die pad size and position, wire length, position and angle, bonding sequence, electrode pad datum point, lead datum point, electrode pad central point, lead bonding teach point, etc.
The DMS DB server 400 stores several kinds of data 410 such as Assy Ref data, Bond Spec data, basic information and bonding rule data.
The DMS file server 500 creates a blank diagram 510, a package outline 520, a bonding diagram 530, a standard file 540 and a chip pad file 550, and transmits them. For example, the bonding diagram 530 can be sent to outside makers 760. The chip pad file 550 is produced from chip layout data as exemplarily shown in FIG. 5. Referring to
The DMS web server 600 is linked to a network (not shown) for allowing the access of a remote user, and provides web services based on the World Wide Web. The network linked to the web server 600 may be a computer network of interlinked using TCP/IP, a local area network (LAN) linked by a coaxial cable or optical fiber, or a wide area network (WAN) such as an integrated services digital network (ISDN) and a broadband ISDN (B-ISDN). Preferably, the DMS web server 600 has a security system such as firewall that enforces an access control when a remote user enters. The security system exists to block bad traffic and to permit certified traffic. The web server 600 can provide web services by drawing up Internet documents with hypertext markup language (HTML), and create active real-time web applications and dynamic web pages by using Java technology of Sun Microsystems, Inc. Additionally, the web server 600 can also make web pages more interactive by using Java applets or common gateway interface (CGI).
The DMS web server 600 includes a blank diagram database 610, a web service for an Assy Ref register/edit 620, a web service for batch modification 630, a package outline database 640, a web service for a Bond Spec register/edit 650, and a web service for a bonder viewer 660. The blank diagram DB 610 is linked to the blank diagram DB building module 700, and the package outline DB 640 is linked to the package outline DB building module 710. The Bond Spec register/edit service 650 is connected to both the CAD data processing module 720 and the BRC module 730. The bonder viewer service 660 is connected to the bonder viewer module 740. A bonder viewer file permits the display of the bonding diagram in the database 410 through the filer server 500. In other words, the bonder viewer can provide prearranged bonding procedure in order on screen so that an engineer can check in advance the bonding procedure before actual bonding process. Data produced in the bonder viewer module 740 are transmitted in the form of text to bonding equips equipment 750.
The blank diagram DB building module 700 and the package outline DB building module 710 will be described later. The CAD data processing module 720 converts data drawn by the CAD drawing tools into data suitable for the bonding process. For example, a centering operation is performed in the data processing module 720. In case of memory devices, the trend of today is toward a center pad type in which the electrode pads are disposed at central portions of the active surface. Therefore, the chip layout and the lead frame blank diagram are often in a one-tone ratio. This requires each separate blank diagram depending on a specific chip layout. Accordingly, to speed up CAD drawing operations, only the connection between the lead of the lead frame and the electrode pad of the chip is defined and used during the CAD drawing operations without defining center points of the lead and the pad. The centering operation corrects a resultant CAD drawing file and provides a standard bonding diagram based on corrected data.
BRC (bonding rule check)
The BRC module 730 provides a function of verifying whether the bonding diagram meets the Design Spec. For example, the Design Spec is prepared based on electrode pad pitch of the chip and, regardless of process, classified according to electrode pad types, package types and/or makers. The package types are QFP (quad flat package), PLCC (plastic leaded chip carrier), DIP (dual inline package), TSOP (thin small outline package), BGA (ball grid array), and so on. The bonding rule includes minimum pad pitch, i.e., a minimum one among distances between centers of two adjacent electrode pads. Based on the minimum pad pitch, the bonding rule is determined. Further, the bonding rule may vary by the minimum pad pitch according to assembly process capability. The bonding rule also includes a large number of rules related to a bonding pad opening (BPO in FIG. 9A), an electrode pad layout for fine pad pitch, a chip pad design by pad pitch, a bonding wire, a chip dimension, and so forth.
The rules related to the BPO prescribe the size of the BPO and intervals associated; with the BPO. Referring to
The rules related to the electrode pad layout for fine pad pitch are applied to smaller pad pitch, for example, 100 μm and less. The fine pad pitch rules prescribe a minimum corner pad pitch, the number of corner pads, a space between minimum corner BPOs, etc. The chip pad design rules by pad pitch prescribe spaces between the electrode pads, peripheral circuitry and the scribe line. The rules regarding the bonding wire define the dimension and angle of the wire. When building the blank diagram DB of the lead frame, a wire dimension database is established according to the package type, the BPO size, and/or the pad pitch. The wire length limits a maximum length from the electrode pads to lead bonding points. The wire angle means an angle between the chip side surface and the bonding wire, generally ranging from 45 degrees to 60 degrees. The rules related to the wires may include a length of the wire passing over the IC chip, i.e., a distance from the center of the electrode pad to the edge of the chip. Too much longer length causes wire sagging that the wire sags and touches at the edge of the chip. The rules for the wires may also include a space between the adjacent wires or between the wire and the lead.
The rules related chip size includes chip pitch, i.e., the size of chip plus the width and length of the scribe line. The chip pitch means a step size in the wafer. The chip size and the scribe line width and length being separately recorded, the chip pad file is created and recorded in the BRC. The rules for chip size may further include a distance from the BPO to the scribe line, a distance from the outermost BPO to the scribe line, a distance from the chip edge to the die pad, and the minimum and maximum of the chip thickness.
Returning again to
In the pre-bonding 241, input data are the blank diagram file and the chip pad file, whereas output data are the bonding diagram file and the standard file. In the Assy Ref edit 620, input data are the bonding diagram file, the package outline file and the chip pad file, whereas output data are the Assy Ref file, the bonding diagram file and the standard file. The standard file is available for the bonding equipments 750 (also shown in FIG. 2), including location data on start and end points of the wires, wire bonding sequence data, wire bonding direction data, datum points establishing data, parameter grouping data, drawing rotation data, data on the origin, data on the number and position of the chips, and the others.
The DMS web server 600 (also shown in
The Bond Spec edit 650 uses the bonding diagram as input data, and then outputs the Bond Spec, the bonding diagram and the standard file. This output is transmitted to the eSPEC server 300 and the bonding equipment 750. The ESPEC server 300 receives the Bond Spec from the Bond Spec edit 650 and sends it to the DMS web server 600. The bonding equipment 750 executes the automated wire bonding process, employing the bonding diagram files and the standard files as input data. The bonding diagram files used in the equipment 750 are output from both the Assy Ref edit 620 and the Bond Spec edit 650. In addition, the standard files used are output from the bonder viewer 740, as well as the Assy Ref edit 620 and the Bond Spec edit 650. The bonder viewer 740 (also shown in
Assembly Reference Review/Edit Procedure
After the Assy Ref is created, the document as the Assy Ref is returned to the document edit (step 1416) and submitted for approval (steps 1418, 1420). If approved, the document is registered (step 1422) and stored in the DMS database 410 (step 1424). If not approved, the document is revised and stored in the DMS database 410 (step 1490). The user can review or search the documents stored in the DMS server 410, together with approval information (steps 1426, 1428). The documents in the DMS server 410 is supplied through web services (step 1430). The remote user 760 can access information about registration or revision of the documents in the DMS server 410 through firewall (steps 1432, 1434).
Further, the web services permit the access of engineers such as assembly process engineers and designers. The, engineers can review the documents stored in the DMS database 410 through the web services 1430 (step 1472), and modify document information such as bonding sequence through the DMS file server 500 (step 1470).
The CAD workstation platform 1010 (also shown in
Bonding Specification Review/Edit Procedure
The user can review or search the Bond Spec stored in the DMS server 410, together with or without approval data (steps 1560, 1562). The approval data in the DMS database 410 is transmitted to the ESPEC database 350 (step 1564). Though generated at the DMS level the approval data including significant information such as drawing data or chip pad file had better be stored in the eSPEC database 350 to assist easier submission for approval.
The Bond Spec documents stored in the CSPEC database 350 are provided to the remote user 760 through web interface (step 1570). For example, when a new Bond Spec document is registered or an existing Bond Spec document is revised, the remote user 760 receives a notification and reads related information through firewall (steps 1572, 1574). Field engineers such as assembly process engineers can review the Bond Spec document through the web interface (step 1576) and, if there is a need to change information such as: bonding sequence, can modify the Bond Spec document through the DMS file server 500 (step 1596). The DMS file server 500 receives the bonding diagram from the CAD platform 1010 (step 1580) and sends the drawing information, such as the Bond Spec, and information on the bonding sequence to the bonding equipment 750 (step 1590).
In the drawings and specification, there has been disclosed a preferred embodiment of the invention and, although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention being set forth in the following claims.